Myelin Sheaths as "Accessories in Clothing" for Individualizing Every Neuron.

Abstract

Here, the model of dissipative waveguide presents an axon where oscillations of ions generate electromagnetic waves that extend at the speed of light in a given medium. A transmission of spikes (wave packets) along axons is perfectly described by the Heaviside-Maxwell telegraph equations, and the instantaneous action potential at any point of the axon is the sum of waves running in opposite directions. Its speed can change in a wide range depending on the boundary conditions of the transmission line. The unmyelinated axon transmits information in the brain without the required precision and synchronization of oscillations owing to the frequency dispersion and disintegration of the action potential in the axon. Opposite, myelin sheaths around the axon increase the precision and synchronization of oscillations because their helical structure and aqueous layers reduce a distributed capacitance and transverse conductivity of the axon, increase its inductance due to the ionic conductivity in the spiral aqueous layer, and reduce a longitudinal resistance of the axon by the parallel conductivity of this multiple layer. Therefore, myelin sheaths transform the axon into an ideal transmission line and, with the help of a diffraction grating from Ranvier nodes, into an interference filter of the spike wave packet individualizing every neuron because spectral characteristics of its spikes are very sensitive to chemical and geometric changes of myelin sheaths that cannot be identical.